LOS ANGELES, Nov. 7 (Xinhuanet) -- Although different genders share the same humor response system, women seem to enjoy humor more than men, scientists reported on Monday.

    Women activate the parts of the brain involved in language processing and working memory more than men. Women are also more likely to activate with greater intensity the part of the brain that generates rewarding feelings in response to new experiences, according to scientists at Stanford University School of Medicine.

    "The results help explain previous findings suggesting women and men differ in how humor is used and appreciated," said Allan Reiss, professor of Psychiatry and Behavioral Sciences who led thestudy.

    These findings, published in the Nov. 7 online issue of the Proceedings of the National Academy of Sciences, could lead to a better understanding of medical conditions such as depression and cataplexy, he said.

    A number of brain structures, including the prefrontal cortex, which is involved in language processing and memory, are known to be involved in humor appreciation. Earlier study also showed thatthe brain's mesolimbic reward center, which is responsible for therewarding feelings that follow such events as monetary gain or cocaine use, is also activated by humor.

    During this study, 10 men and 10 women viewed 70 black-and-white cartoons and then rated the cartoons on a one-to-10 "funniness scale." During the screenings, the researchers used functional magnetic resonance imaging to monitor participants' brain function. They then analyzed blood oxygenation-level-dependent signal activation, a measure of neuralactivity, in various parts of the brain.

    The researchers found that men and women share much of the samehumor-response system; both use to a similar degree the part of the brain responsible for semantic knowledge and juxtaposition andthe part involved in language processing.

    But they also found that some brain regions were activated morein women. These included the left prefrontal cortex, suggesting a greater emphasis on language and executive processing in women, and the nucleus accumbens, or NAcc, which is part of the mesolimbic reward center.

    Reiss and colleagues theorized that because women used more analytical machinery when deciphering humorous material, it signaled that they were not necessarily expecting the cartoons to be as rewarding as did the men.

    When a woman's brain encountered the punch line, her reward center lit up. According to Reiss, the activation of this center not only signals the presence of something pleasant, but that the pleasure was unexpected.

    "Women appeared to have less expectation of a reward, which in this case was the punch line of the cartoon," said Reiss. "So whenthey got to the joke's punch line, they were more pleased about it."

    The researchers also found that the funnier the cartoon, the more the reward center was activated in women. That was not the case in men who seemed to "expect" the cartoons to be funny from the start.

    If subsequent studies show that women's reward center and otherregions of the brain are more sensitive to emotional stimuli, including negative stimuli, that could help explain why depressionstrikes twice as many women as men, potentially leading to new therapies, Reiss said.

    The results also have potential implications for individuals who suffer from cataplexy, in which a sudden loss of motor controlis precipitated by strong emotions, most notably humor, he said. Enditem